Valve assembly

Abstract

The valve assembly has inlet and outlet members with valve elements disposed between the two members. The valve is a resilient membrane having one or more through holes. When there is no pressure differential across the valve, the hole walls in the membrane collapse inwards closing off the valve against liquid flow. At or above a threshold pressure differential across the valve, the membrane is stretched which opens up the hole or holes to allow the passage of liquid.

I claim:  
     
       1. A valve assembly for liquid transfer, the valve assembly comprising: 
       a housing having a liquid inlet, a liquid outlet, and an intermediate liquid port, said intermediate port having an inlet and an outlet;  
       a first perforated support plate located between the outlet of the intermediate liquid port and the liquid outlet;  
       a second perforated support plate in the housing located between the inlet and outlet of the intermediate liquid port;  
       a first valve member positioned in the housing located between the first perforated support plate and the liquid outlet and adjacent the first support plate, the first valve member comprising a resilient membrane having one or more holes through it, the holes open upon deformation of the resilient membrane at a selected threshold pressure over the resilient membrane to permit liquid flow through the resilient membrane but which otherwise prevents liquid flow, the support plate preventing the resilient membrane from deforming sufficiently towards the liquid inlet for preventing flow to the liquid inlet; and  
       a second valve member being positioned between the second perforated support plate and the outlet of the intermediate port and adjacent the second support plate, the second valve member comprising a resilient membrane having one or more holes through it, the holes open upon deformation of the resilient membrane at a selected threshold pressure over the resilient membrane to permit liquid flow through the resilient membrane but which otherwise prevents liquid flow, the second support plate preventing the resilient membrane from deforming sufficiently towards the inlet of the intermediate liquid port for preventing flow to the inlet of the intermediate liquid port; and  
       a single pump so constructed and arranged to pump liquid from a first container through the first valve member, upon being reversed, the pump sucks liquid through the second valve member from a second container, and upon being reversed again, the pump pumps liquid through the first valve member.  
     
     
       2. A valve assembly according to claim  1  in which the threshold pressure for any resilient membrane is determined by the thickness and surface area of the resilient membrane and the size of the one or more holes. 
     
     
       3. A patient feed system comprising: 
       (a) a valve assembly for liquid transfer, the valve assembly comprising:  
       a housing having a liquid inlet, a liquid outlet, and an intermediate liquid port;  
       a pair of valve members positioned in the housing, a first valve member being positioned between the outlet of the intermediate liquid port and the liquid outlet, and a second valve member being positioned between the inlet and outlet of the intermediate liquid port, each valve member comprising a resilient membrane having one or more holes through it which open upon deformation of the resilient membrane at a selected threshold pressure over the resilient membrane to permit liquid flow through the resilient membrane but which otherwise prevents liquid flow, each resilient membrane being deformable in a flow direction; and  
       a pair of perforated support plates positioned in the housing, each perforated support plate being associated with a resilient membrane for preventing the resilient membrane from deforming sufficiently in a flow direction opposite the one flow direction of the resilient membrane for preventing liquid from flowing out of the liquid inlet or into the liquid outlet;  
       (b) a first liquid nutrition container connected to the liquid inlet;  
       (c) a second liquid container connected to the intermediate liquid port; and  
       (d) a luer-type connector located at the liquid outlet for connection to a feed tube; and  
       (e) a single pump so constructed and arranged to pump liquid from the first container through the first valve member, upon being reversed, the pump sucks liquid through the second valve member from the second container, and upon being reversed again, the pump pumps liquid through the first valve member.